This invention relates to an epoxy resin composition suitable for use as a casting resin for packaging of a coil such as an ignition coil.
An ignition coil for automobiles is generally packaged in a plastic casing together with primary and secondary terminals. The packaging, which is generally called "potting" is carried out by placing the coil and itd associated parts within the casing, filling the space within the casing with a casting resin, and curing the resin.
Such a casting resin should satisfy the following requirements: (1) the resin can smoothly penetrate into the interstices of the coil windings, (2) the resin can be cured within a short period of time, (3) the resin can be cured with minimized generation of stresses, (4) the cured resin can withstand a high voltage and (5) the resin should not corrode the materials constituting the coil. Known casting resins including known epoxy resin compositions are not fully satisfactory because some of the above requirements cannot be fully met thereby.